In many databases, when you see something like int(11), you would expect 11 to be the maximum size of the field but for some reason the MySQl folks thought that was too intuitive so they decided to change it. In MySQL when you something like int(M), M stands for “Maximum Display Size”.

"M indicates the maximum display width for integer types. The maximum legal display width is 255."

Reference:
Mysql Websites
http://dev.mysql.com/doc/refman/5.0/en/numeric-type-overview.html

Other Resources
http://www.dbforums.com/mysql/1624054-int-m-mysql-what-does-m-mean.html

Which one should I download JRE or JDK?

JRE enables you to run java applications

JDK enables you develop java applications

“What Java Do I Need?” You must have a copy of theJRE (Java Runtime Environment) on your system to runJava applications and applets. To develop Java applications and applets, you need the JDK (Java Development Kit), which includes the JRE.
http://www.oracle.com/technetwork/java/javase/downloads/index.html

Clearing your floats or setting up your Overflow Property for your parent Container div should fix the issue. 
Also avoid setting div box height property for div box that you know for sure  is going to have text.

Overflow:hidden
http://css-tricks.com/2833-the-css-overflow-property/

Clearing Floats
http://css-tricks.com/795-all-about-floats/