We have extensive guides at the top of the newbies section. Please put some effort to read through them first. Also, please have a more accurate description in your title. Simply "How to" is too vague, and relates nothing about the thread.
Welcome to CS Here's how you can post your photo here in the relevant sections >
> To post from flickr > click on your image, choose size (usually the bigger size), copy the link, start new thread or reply in CS, click on the landscape pic, paste your link there & voila..................you have posted your photos
Posting a new thread is the same like how you posted this thread