Posting attachments for 1st timers

I just posted a picture for the first time so here's what I did.
1. click on post new thread
2. go down to manage attachments -click
3. Checkout Attachment Key to see "file size" for your picture file type
4. Go to your picture and right click then click properties to see pic. size
5. If you are max. size or smaller go to #9 below if too big go next step
6. Left click on pic. then go to bar at top and click Image then click Resize
7. Follow instructions to resize I had to chose 800x600 pixcels then click OK
8. Go to file at top and click save then yes. Now pic. s/b correct size
9. Go back to post new thread, click manage attachments, click browse
10. Find your picture, left click on the pic., then click open.
11. Picture s/b now attached and ready for your message. Post as usual.

Now this explanation is from someone that knows squat about pc. I had to figure this out by myself so if you computer pros have a better way please help us guys out...This may be different for other computer program thingys.