First off I have to say that the way I did it might not be the best way since I used to a text render which is affected by the light in the level whereas a traditional HUD isn’t affected (Not 100% sure since I don’t have that much HUD knowledge). With that said I think it might be possible to use the same technique with HUD blueprints to avoid that problem, so here is the explanation.
First you’ll need to create a socket in your character’s skeleton so that it can be used as an anchor for your HUD. Open the skeletal mesh you want to use, in the newly opened window select a bone you want to add a socket to (it should be a bone near the location that you want to show your HUD", right click it and select “add socket” then move that newly created socket to the exact location you want it to be, give the socket a name so that it can be used later on. The image below shows how it looks once completed.
Then it’s easy to attach a plane with a texture or a textrender to the socket you created with a “Attach to” function, just plug what you want to attach into the “target” pin and plug the character mesh in the “parent” pin, then put in the name of your socket in the “In socket name” field and select “Snap to target” under attach type.