ok. let's get it simpler. this can be done without the command line .
1download the firefox from the mozilla site to your desktop .
2on your dekstop you should have a file now named firefox and there says it's version in the name ..
3right click on that file and click °extract file here° if you see that option . if not , then double click on it.
4if the right click thing worked , go in the decompressed directory , should be named firefox . find a file named firefox and double click on it . it should be firefox with no other thing around
55with double click , look on top of the windows that just opened . there should be some extract here or something like that option.
if that worked , follow option 4 from the second sentence to the end .