I'm sorry I'm very good at putting instructions into words but here goes:
-Grab the snake by the back of the head gently but firmly
-get the pinky, fuzzy or whatever size you are using and dip into water
-grab the mouse near the head
-gently work the head near the back of the mouth
-the snake should open its mouth fairly easily
-don't get frustrated as it is easy to do the first few times
-gently push the mouse towards the back of the mouth to where she has no choice but to swallow (this might take a bit of wiggling around)
-don't force it down
-put her down gently into her feeding area and walk away quietly
-she should hit the feeding response and start to swallow but try not to be disappointed if she doesn't take it happens.
if she doesn't take, then let her be for a few days to get over the stress you just put her through and you may try it again if you don't feel comfortable doing this then I suggest to take it to a vet and they will force feed it.
Good luck let us know how it goes.
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Louie