Hi Avni,
Which software are you using for schematic editing?

I have used Orcad(Good Old DOS Version and Windoz versions), Eagle, etc.

1. Most of them have an option of exporting the schematic diagram to Bitmap File; usually a ".BMP" file. Convert it into GIF image.
OR
If your software does not have the option of exporting, then bring up the schematic in your software, Press the "Alt+PrintScreen" button, and in Windows Bitmap Editor save the file as GIF.

2. go to
http://www.8052.com/homepages
At the bottom of the page look out for the :
"To create your own 8052.com home page for free, click here." Click on the link.

3. Now you can upload your files here. Watch out for the file sizes.

4. Now click on the File you have attached, note its Website address.

5. In your posting on the forum, Click on the button "Insert Image", now enter the Address of your Image file from your user page.

And remember to preview your post before posting it on the forum.

Edit:
Using the same method, I had extracted, and posted a part of the PDF File (image) and posted on this forum in this post:
http://www.8052.com/forum/read/173458
Those 3 images are on my user page.