Dear Saraswatimaa, please open any thread. See at the bottom of the thread, there is a "post your comments" box available. Below the comments box, please click on the blue box "Start New Topic". You can select the appropriate subject to which your thread is related, and click on "Start New Topic/Share Files/Formats". Then, you can type your subject heading, ask your query, and share the knowledge and articles you have.
To attach any file, click "Manage Attachments" and attach the files. You can change the script size and color with the help of the toolbar available in the Message Box.
Please do not upload any copyrighted materials, as that could cause problems for you as well as the forum.
All the best and happy learning.