To give yourself permission to execute a file that you own:
chmod u+x file1
This gives you execute permission for the file "file1".
To give members of your group permission to read a file:
chmod g+r file2
This gives the group permission to read the file "file2".
To give read permission to everyone for a particular type of file:
chmod a+r *.pub
This gives everyone permission to read all files with the extension .pub.
To give the group write and execute permission:
chmod g+wx $HOME/SCCS
This gives all members of the group permission to place files in the directory SCCS in your home directory. They can also list (ls) the contents of this directory.