Hi there, Bonnieheather. I think I can help you, or at least I'll try to. For the first part of your question, if you go to the large Apple Icon at the top left of your screen, and then go to "About this Mac" it'll give you a model number and a year. According to the quick look I did, you have El Capitan. If you want to upgrade past that, your Mac will have to meet the system requirements for Catalina or Mojave. which you can find out by using yahoo, google, or going to the App Store and seeing if you can find either one, and somewhere on its page-for Catalina or Mojave-it'll tell you the system requirements before you try to download and install it. As for the 2nd part of your question, did you have Office and/or Word before ? If you did, then see if you can update it to work with El Capitan. If not, then you could think about buying it, or using TextEdit (if you want to make a simple word document, just if you want to write something.....it's basic, but it works. If you had "Pages" on your hard drive, you could use that. It used to be that Apple would include a copy of iLife, which included Pages, Numbers, iDVD and a bunch of other useful applications for free. But, that was then, and this is now. You may not have gotten a copy for free. In that case, you could think about buying it or trying OpenOffice (LibreOffice) which does most of the functions of MS office, and can open MS office documents, but it's free, as in, $ 00. Again, I don't know if you had Microsoft Office before, or Pages before, but I have given you a few suggestions which you might find helpful. I'm just a Mac user here same as you, and we help each other out.
Hopefully I have managed to help you out a bit, Bonnieheather. If you have any more questions or need more help, please feel free to reach out and post your questions, and I'm sure someone will reply and help you out shortly.....
John B
