~ is for accessing your home directory , if you type cd ~ you will reach your home directory.
For example you want to go to Music directory from any directory just type:
cd ~/Music
If a directory name starts with dot . it means that is hidden however you can access it from cd .foldername, also there are other uses of dot like:
1) cd . u remain in the same folder where you are before entering this command
2) cd .. go to previous folder from the current folder
NOTE : Folder and Directory are used interchangeably