hate to ask but I would like to post some f mine how do you do it
This might be easier to show with a video, but...
Image tutorial time!
First off, unless the whole scene is what you're showing, please crop the silly thing. You can do this in MS Paint under accessories, don't need Photoshop or anything. (I use GIMP for image editing, it's 100% free open source software.)
Open your screenshot in Paint or GIMP or Photoshop or whatever. Crop it down if needed. Export or Save As... so it's a smaller (usually) file, and name it something that makes sense so you can find it later without browsing previews (DAI_My-mage.png etc.). Save it to My Documents/Pictures or somewhere outside the screenshots directory, so it's easy to find.
Go to imgur or a similar service. Imgur is great because you just upload something, click on it in your gallery, and it provides you with a list of links on the right. Click on and CTRL-C copy the "Direct Link (Email & IM)."
Now, this part do slowly the first time, once you do it a couple times it will be easier to remember. This isn't the only way but IMHO the cleanest and best way to show off large shots without having to resize the forum page.
Go to the post you want the screen shot in. Paste the link you just copied twice on two different lines, like this:
(I put spaces in the HTTP so the forum wouldn't turn them into links when I post this. Don't do that, just paste them normally.)
ht tp://i.imgur.com/w4nKLbB.png
ht tp://i.imgur.com/w4nKLbB.png
Now you have to add an s to the file name of the top one only, before the .png, after the string of letters and numbers, so you have this:
ht tp://i.imgur.com/w4nKLbBs.png
ht tp://i.imgur.com/w4nKLbB.png
Now copy the top one with the "s" and leave it highlighted. With that line highlighted, look up at the editor bar and click the Image icon. It's to the left of the Code button (which looks like < > ). A window will pop up asking for a URL; CTRL-V paste your URL with the s on the end into it and hit OK. This will happen, with the second link still below it (with no S):

ht tp://i.imgur.com/w4nKLbB.png
Almost done! You have a thumbnail but it isn't a link to the full-size image yet.
Copy the s-less link, then click your little image so it is highlighted, then click the Link button in the editor bar, which is the chainlink with a green ball and is two buttons left of the Image icon you clicked a moment ago.
Another window will pop up. Ignore the drop-downs and just paste the URL into the text line, then click OK. You won't see anything different on the screen, but that is it. You can now delete the text of the URL that is below the thumbnail.
You can't see that it's there, but the thumbnail is now a link to the full-sized image on Imgur, which when clicked will open it in a new tab and leave your forums tab alone:

Tada! It takes a few minutes to run through the steps for a picture, but once you do it a couple times it'll be easy to share, and forum viewers will be able to see a full-sized shot that doesn't exceed the forums window.