I understand you have some executables in one of your home folders, e.g., in ~/bin and you want to be able to execute them without always typing the full path ~/bin/my_cool_executable.
You already observed that entering PATH=~/bin:$PATH in your terminal made things work... but only until you close the terminal. When you open a new one, your former PATH variable gets reset to its original value. By the way, I guess you know how to, at any time, check the value of the PATH variable: like so:
echo "$PATH"
How to make your change permanent so that your PATH will still be the same when you reopen a new terminal? It's very easy, you just need to edit your .bashrc file. Let's use the gedit editor: In a terminal, type this:
gedit ~/.bashrc
This opens up the gedit editor. Scroll to the end of the file and add this:
# Added by me on 2013/06/24
PATH=~/bin:$PATH
export PATH
and save the file and quit gedit. Then close your terminal and open a new one. Now your PATH variable should have ~/bin in front of it so that your commands in ~/bin will be accessible without typing their full path. And you know how to check that: echo "$PATH".
Enjoy!
Warning. It is considered bad practice and a security vulnerability to put . in your PATH variable.