If you have any problems during the installation of MySQL, the first place you should look is the "Problems and Common Errors" chapter of the MySQL manual, which is located at http://www.mysql.com/doc/P/r/Problems.html.
The following are some common problems:
On Linux/Unix, Incorrect permissions do not allow you to start the MySQL daemon. If this is the case, be sure you have changed owners and groups to match those indicated in the installation instructions.
If you see the message "Access denied" when connecting to MySQL, be sure you are using the correct username and password.
If you see the message "Can't connect to server", make sure the MySQL daemon is running.
When defining tables, if you specify a length for a field whose type does not require a length, the table will not be created. For example, you should not specify a length when defining a field as TEXT (as opposed to CHAR or VARCHAR).
If you still have trouble after reading the manual, sending e-mail to the MySQL mailing list (see http://www.mysql.com/documentation/lists.html for more information) will likely produce results. You can also purchase support contracts from MySQL AB for a very low fee. If you have purchased a version of MySQL other than the one distributed by MySQL AB, you should turn to the documentation and support options for that product. The companies that sell other versions of MySQL usually have additional support contracts that you can purchase.