Well done.
Don't bin the better of the old seals yet. Scrape as much rubber off as you can, round the outside.
Make sure that the housing is cleaned up, I use a pen knife, gently picking any bits of rubber that sometimes get left behind.
Put a thin smear of grease on both the seal and the housing.
Position the seal and push it in as hard as you can with your fingers. All you need is for it to grip in the housing.
It is important to keep the new seal going in at the correct angle, and the best way to do it is to put it in a vice, across the diameter, and squeese the seal in about 2mm, then slacken and turn through 90 degrees for another 2mm, and so on till it is flush.
Using the old seal on top of the new one, you can now push the seal into its final position.