Hello Tajinder
Yes, experience letter is necessary and at least 1 year exp. is required for applying your case under Skilled worker (MPNP).
You can make your exp. certificate on the letterhead of the company/ firm in which you are working.
In that certificate mention your Key responsibility area as well as you salary /wage during period.
Remember one thing this exp. certificate must be signed by your Boss / Senior and must be stamped by the company under which you are working.
Hope you will got some idea.
Gud luck.