Trouble shooting & Guide clarification:

This is only to add on to the main guide, and is not in any way a replacement. Always read the main guide first.

Make sure that all of your tulpa's attention is on the body; he/she must fully tune out the wonderland/mind/imposed environment and shift their focus to the body. You can have your tulpa focus on the body's senses such as hearing, taste, and most importantly sight. If you are sitting down on a chair make sure your tulpa gets that same feedback: he/she should feel the chair underneath the body.

Your tulpa needs to change his/her perspective: they are not watching the body anymore, they are the body. Your tulpa need to assume the body is theirs, just like how they have a sense of ownership of their wonderland bodies. Move your arm around a bit yourself. From your tulpa's perspective the body should feel like it's moving on its own. If you can talk to your tulpa then try to confirm this, otherwise you can skip this step.

Now rest your dominant hand on your lap or on your desk or whatever else you prefer. Tell your tulpa that the hand is theirs and it's a part of their being. Ask him/her to try to move the index finger, and they will move this finger like it belongs to them. That means no 'thinking' about moving it, they will move this finger in the same nature as they will move their wonderland bodies, by direct command - just like how a host will move their body. Even if the body don't move at first, just keep pressing on. Once your tulpa gets past that initial resistance of moving any part of the body, it will become much easier to maintain that control.

As for the host, they need to try their best not to interfere. After your tulpa has moved the finger, don't try to take back control or move it under your will in any way. Doing this reinforces all of the resistance that tulpa had to get through in order to gain control of the part in the first place.