Hey moog, and welcome to the site. Hope you enjoy things here. There are several programs that enable you "shrink" your pictures. The easiest one I know of and the most common is Microsoft Office Picture Manager. Right click your picture and select "open with" and see if that is one of your choices. If it is, simply select that program to open the picture and then select "Picture" from the file menu at the top. From there select "resize". If you do not have this program, tell us what you do have and we'll see about getting it done on that. If you don't have anything, we can probably point you in a direction to download something for free.
For posting pictures on the site, you can do it one of two ways. you can click the "additional options" (in red right below the text box when you are writing a post) and select the browse button to find the pictures. You can add a few more this way too. The other way is to create a photobucket account and tag the image into the post. This is done pretty simply too. Once you have a picture uploaded into photobucket it has the tags already for you, all you have to do is click on the "IMG" tag and then come to the post and "paste" it in by right clicking.
I hope this helps a lil bit??