I am planning to start a site in which the content is generated by the users. What is the best method to save the data submitted by user?
Is the method of saving the data in phpmyadmin database a good idea considering that the data submitted by users is large similar to a blog post. Btw I'm good in working with php and mysql but I'm not sure whether it is a good method.
By 'phpmyadmin' database I assume you just mean a MySQL database.
Since your user data is basically a 'blog post' - basic text and HTML, and you'll most likely be storing username, posting dates, titles, and the like as well -- a MySQL database is a fine place to store it.
If you're using standard shared hosting, your options are pretty much a relational database (MySQL) or a flat file. Between those two choices, a relational database is the better option.
Not sure just what you're asking here - If you're thinking of actually trying to save a .jpg file and text as blobs physically stored in the database, don't. Not if you intend to have a lot of users all uploading stuff. Look into saving it on your server in a folder for the user or better yet to the cloud - it'll be cheaper in the long run and save you tons of anguish with a corrupt database.