How can I get more application memory on my iMAC?

If you have a 21.5" iMac as your profile indicates you need to tell us the model year. Not all 21.5" iMacs have RAM that is upgradeable and NONE of the 21.5" iMacs made from 2012-2020 had user upgradeable RAM. If you own a 21.5" that can have the RAM upgraded it takes a 100% disassembly of the computer to upgrade which is expensive and will not improve the speed of the computer!!!!!

It would be helpful if you told us why you believe your Mac needs more RAM. To be really really honest if your iMac is a 2012-2020 iMac, don't waste any money on upgrading the RAM, simply replace the computer with a new Mac Mini or other Mac which will significantly improve performance and future proof you for the next 7-10 years. If this is something you would be willing to consider we can help steer you to the best solution for your needs, we cannot at the moment as we have NO idea what your needs are.

You could start by telling us the exact model iMac you have. Do Apple > About This Mac and either post a screenshot or tell us what it says for model, processor & memory.

Here is an example: