How do I resize jpg pic?

Hey all,
Well, Im still fairly new here obviously, but Ive been updating my profile with info and pics...I have a few cool pics of me in the desert smokin with my buds in uniform from an awsome bomb Thompson CO sent me...Anyway, Id like to post these pics as well, but it seems the pics are too big. The pics are JPGs, but are 4.20 MB and 3648 x 2738 pixels...in order to post a pic in my album it has to be no more than 97.7 KB and 600 x 600 pixels..

Is there anyway for me to downsize these pics so I can upload them? Any advice or info anyone has would be greatly appreciated. Thanks and have a great and blessed day!