My MacPro is not allowing me to upload new operating system above OS X Yosemite. Is there anything I can do to upgrade my computer. Do I need to add more memory?

The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.

With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install. Make sure to use Only Safari to commence the download as Others may not work. Safari will open a redirect and open the Apple Store where you can commence the download. If an error message appears, that is probably because one is using another Browser.

Suggest using Go64 to find 32 bit application before attempting the upGrade. Some or many of the Application already installed may required update or upGrades to 64 Bit Versions.

Make a Time Machine Backup Before attempting. Notation - Mojave is the Last version to support 32 bit applications / extensions and Drivers. Catalina & Big Sur supports only 64 bit and there is no workaround.

Are there any AntiVirus, Disk Cleaner, Optimizers, Un-installers, etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation

Follow to advise of @ Ronasara regarding adding RAM and such to the computer.

As for Space Issues >>

What is “Other” storage on a Mac, and how can I clean it out?

Free up storage space on your Mac

OmniDiskSweeper safe to use

See used and available storage space on your Mac

Below is as per Apple on Managing the " Other " Category

• Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Adding memory won't make any difference. If you have already tried to upgrade and can not, then the reason likely is because your Mac can not accept a newer OS. What it can accept depends on what yer and model you have. (Which you have not revealed.) If you tell us what you have, then we can advise you whether it can be upgraded.

I cannot install Monterey- it states that I don't have enough free space to install I need additional 17.1 of space. How can I increase the needed space to install the upgrade Monterey. I have MacBook 13 inch 2017 memory 8gb. How can I upgrade the memory to 16 or 32 gb? Can I buy the memory chip from Apple and install it myself or do I have to go to an Apple store or Best Buy Geek squad? If I can install it myself where will I find the directions on how to install the memory chip?

I think I can help you further understand the situation. When you receive a message that says you do not have enough space, that means available storage space on your computer's hard drive. This is completely different from memory which is stored in the computer's RAM. RAM affects how fast the computer functions, or its performance, not storage. The computer needs a certain amount of available storage space in order to accept the downloaded installation file. You seem to not have enough storage at this time. This can be corrected by one of two methods. (1) delete a sufficient amount of unneeded files from the hard drive. Then be sure to empty the Trash. Or, (2) Purchase and install an external hard drive. Next, transfer sufficient files to that drive. Then delete those files from the hard drive and empty the Trash to clear the needed storage. These days, external drives are cost effective, they work reliably, they are easy to install with vendor provided USB cables and most do not require any external power. You may have to format it thought. Easy and done. Problem solved.

Thank you for your help. I have an external hard drive I’ll transfer files and follow your directions.

You are most welcome. I'm glad I was able to help you.