Method #1: MS Paint
Software Needed:
- MS Paint
This is probably the quickest method, seeing as everyone already has everything they need to resize your images installed on your PC. First you will need to open MS Paint. This can usually be done from accessing the start menu > accessories and then clicking 'Paint'. If you cant find it this way hold down the windows key on your keyboard and press R (the letter), then type 'mspaint.exe' (without the quotation marks) in the box that pops up and it should start.
Once Paint opens, you will need to click File > Open, and then navigate to your image file using the file-browser that pops up. Once you locate your file, simply double click on it to open it in Paint. Once your image loads, simply click File > Save As, and save your file under the same name, or a different one if you prefer to keep the original file intact. I prefer to use the file extension '.jpg / .jpeg' as this is one of the most widely known and recognised image formats and is accepted at any image hosting service.
This method probably isnt the quickest one available, but as I said before, it is the easiest because you dont need to download any extra programs to do the job. Also, the quality is still quite good when done this way as ]well, even though it reduces the file size drastically.