Multitasking

If your iPad is on iPadOS 15, there should be three dots, at the top center of your iPad's main screen area that control multitasking windows on an iPad.

There is nothing more to “setup”. Multitasking is an intergral part of iPadOS 15, now.

You can turn/toggle on/off multitasking windows, using the three dots at the top center of your iPad's screen, at any moment.

Best of Luck to You!

If you cannot upgrade that iPad immediately and your iPad is still on 14.7, you can go into the Settings app under the Home Screen and Dock settings panel and tap the Multitasking Panel, toggle on Allow Multiple Apps, and you have the option of toggling on finger gestures that are used to activate iPadOS multitasking.

Here's a link to Apple's iPad Users guide for iPadOS 14.7 here to help with features and multitasking features in iPadOS 14.7.

Tap the link below

https://books.apple.com/us/book/ipad-user-guide/id1515995498

Best of Luck to You!

If your iPad is capable of being updated to a more recent version of iOS/iPadOS than is currently installed, these support pages outline both the available methods by which the update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

iPadOS15.7 is current.

Be aware that while an iPad may be capable of update, it may be too far behind the current version to be updated directly from iPad settings. In such circumstances you will likely need to use a computer to perform the update. You will need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

If you have a beta profile installed, ensure this has been removed from your iPad - as, otherwise, installation of production software updates may be inhibited. This support page provides the necessary information to remove the beta from your iPad:

How to uninstall iOS beta software - Apple Support

You should note that for your iPad to install an available update, its battery must be charged to at least 50% capacity - and/or be connected to its Power Adapter. Similarly, the iPad can only be updated over a standard WiFi connection - or be updated by a PC or Mac using iTunes or Finder - over a USB connection.

Multitasking

Multitasking in iPadOS14.x was quite primitive when compared with the iPadOS15.x implementation. While many of the control gestures of ‘14.x remain, the principal method of invoking and switching between full-screen, split-screen and slide-over views are now controlled using the three-dot button that appears at top-centre of App windows.

More information about using multi-tasking in iPadOS15 can be found in this support page:

Use multitasking on your iPad - Apple Support

The iPad User Guide is also a rich source of information about using iPad and its many features. The Guide is available both online using a web browser (such as Safari), or as an Apple Books download:

iPad User Guide - Apple Support

https://books.apple.com/book/id1567104892

You should upgrade that iPad to patch a security vulnerability that became present when iPadOS 15.6 came out.

Your iPad is way too far behind in iOS/iPadOS upgrades/updates.

If you have access to a full computer, like a Mac or Windows PC, try either using the Finder on a Mac that has the newest macOS Catalina, or later macOS, installed OR with an older Mac with an older Mac OS, download and install the latest iTunes version ( or latest iTunes for Windows PC ), make sure the Mac or Windows PC is connected to the Internet, connect your iPad by the USB charge cable to the computer and let the iTunes application upgrade/update that iPad model, using the iTunes Software Update feature, to its current, maximum OS of iPadOS 15.7.

Make sure your iPad is, at least, charged to 50% or greater to attempt this.

Also, make sure your iPad has, at least, between 6-8 GBs of free internal data storage space for downloading and installing a major iOS/iPadOS upgrade.

Make sure your desktop/laptop computer has plenty of internal drive storage space, also.

Also, make sure to do a backup of your iPad's data, prior to upgrading/updating.

Backup to Apple iCloud and/or a full Mac or Windows PC using the same iTunes app OR, if a newer Mac running macOS Catalina, or later, making a backup using the macOS Finder app.

If NO access to a Mac or Windows computer, you will have to seek help from a good friend or family member, with a full Mac or Windows PC, to help you out

OR

Search online to locate and call contact your nearest, “local” Apple Store location to try/attempt to make an appointment to get your Apple iPad upgraded/updated to its latest iPadOS 15 version.

OR, alternatively, use the “Get Support” link, at the upper right hand corner of every Apple Support Community Webpage to attempt to schedule an appointment with your nearest Apple Store location.

Apple Store employees will be glad to help/assist you.

Best of Luck to You!