You can do it Yourself !
I cover this process thoroughly in my pages on building a djembe. The main difference is you are working with a djembe with a head mostly roped on already. Take the time before you start to read my djembe heading pages and you will be prepared.
*Note on photo the loop where the vertical rope connects to itself. This is where you untie the rope that goes through the loop, and the knot if you can get it loose (else cut it), back out each rope end through the "Cradle Ropes" until 1/4 of the circumference of the vertical rope is removed. Instructions Below!
This is the time to make any repairs to your drum, so please consult - What to look for in a Djembe - and inspect your drum first. Decide if you need to do any of these :
Repair the djembe drum shell. (Fix or fill any cracks. Refinish. )
Rework the wood playing edge (If it isn't nice and comfortable round it like your thumb profile.)
Replace worn or low quality rope (If your drum won't stay tuned, this may be the culprit!)
Resize the rings to a better fit. (If the rings are too big this will contribuet to a shortened head life.)
If your djembe drum needs these kind of repairs, the new head result will be limited by the drum's current flaws!
To prepare and remove the existing goat skin head:
First remove all tuning diamonds - Find the end of the rope that has been crossing the vertical ropes and back all that out till you just have vertical rope.
Find and untie the knot that joins the ends your vertical rope. (See Photo)
Back out between 1/4 and 1/3 (of the circumference)of your vertical rope out of the rope cradles at top and bottom (it helps to work from both rope ends a little each way)
Now work the slack into the vertical rope you have left threaded (maybe 2 inches in each rope) enough so the whole top ring can rise up to just above the level of playing surface.
You should now be able to slide the hide ring with the old head out from under the top rope ring, through the 1/3 gap you left in the vertical ropes.
You are now ready to use my Djembe Heading Instructions! Don't worry just take your time and pay attention....You can do it! This page verbally guides you through preparing and replacing the new skin
Skin or Head
A good quality goat skin head is critical. Defects like bot marks (scars or thin spots from insect bites) or whip marks (line scars) should be avoided.Common wisdom is a female goat is best, but the main issue is that the skin be of relatively consistent thickness across the spine. A Pakistani or domestic goat skin is likely chemically treated and as such the hair folicles have been burned out leaving a microscopic, "sponge like" surface. I believe the density of an African shaved, untreated head is best.
Look for a skin that is without nicks or scar flaws, or any weak spots. It should not have any folds where it passes through the rings, when installed. Whether it is hair, on or off, or wrapped over the rings, or cut flush is all personal preference. A very heavy skin will give you a very dry slap with little over tones but it is very hard to fully tune and it is like hitting a board to play.