Step 1
First..of course you need a image.
Step 2
Use pen tool->zoom in->highlight the part that you want to be colourised->link the last dot with the begining of the dot->right click->make selection->copy(ctrl+c).
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihI3MqKnAQPCRdX51_ZGAZGt9gWJU7l0hLoczbAyZRUZmz_Wo_DxTeLUF6ADjKb_W4cNxz803uZIuR70j1QiM-kPqNvGI1commMO0hqXO5qHn6ndIGr-KO3M3PPLrTd0yKWTEoGa8n1ss/s400/m1.jpg)
Step 3
Make a new layer and paste the selection on there.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiNF9CN7l59BEJ0TReCCFF1WXpSoOain-0oB3D-HBfc61G0DytapOOYc5hnx25fOiELzu0m35-nw8AUGXO6_b3JIZHhehZD9WQnc8TQ1WkQ7t9v14ipgwzWH3Zxp_coeenk-9MVp1JXMo/s200/m3.jpg)