Air lock in heater pipes?

Hi, I'm sorry, this is going to sound so basic, I'm sure It'll bore some people to death, but I'm completely non-technical so need a bit of advice.
The heater in my Jimny isn't working. The radiator is fine, the blower is blowing, there's just no heat. It's fine for now of course, but come winter, it will be a different story.
Very kindly, someone from the site suggested it could be an airlock in the heater pipes, but....
How do I find out and is it something a complete novice and a complete clutz could do without causing irreparable damage and making it a whole lot worse?

If you have drive on ramps
Drive up them forwards to make the radiator cap the highest point
(If no ramps steep hill/grass bank or anything)
remove radiator cap (better with engine cold to avoid scolding yourself)
run engine heater on hot and full fan
squeeze top and bottom radiator hoses
this should get any air out

Or it could be the control leaver under dash near clutch pedal (these can fall apart)

This thing check it moves when you operate the heater controls

If it's not an air trap or heater control as above ^^^^ it's possible the matrix is blocked. You can try flushing with a hose pipe by removing the heater matrix feed pipes, but it's best done during a coolant change as you are going to loose coolant in the process. The matrix feed pipes are shown in the photo.
These should both be hot if water is flowing into the matrix, so you could have a feel and let's us know if they are warm or not.

Hi Jack, Thanks, the heater control under the dash, should it be 'one' unit, (the two bits linked together) mine is two bits - the top and the bit with the wire aren't joined together?

Yes should be linked
In this picture you can see a the pivot point


This picture is set to hot on heater

Blimey!!! - Thank you so much - it works, I just put them back together and whammo! - You've saved me a trip to the garage, all their flannel and probably money I can ill afford, I'm overwhelmed...it's been like that since last year, Thank you.

Happy to help Pal
Rains stopped play for me today