Using a large amounts of seeds will significantly influence the humidity of your dough and bread. Dry seeds will soak up quite a bit of water - either during resting time or afterwards. This is especially bad when this soaking happens after baking, as your bread will get very dry... Wholemeal tends to have the same effect.
The best way to counteract this effect is to
- add more water and
- add more time
This can be done either by
- pre-soaking the seeds, which will then "bring" the required extra water to the dough or
- letting a rather wet dough rest for a long time, preferably over night.
The first approach is easier, because the seeds take up the required water "automatically", the latter preferable taste-wise. Longer resting times allow for the development of complex flavors and need very little yeast or sourdough.
As for recipes, you should be able to find plenty on the internet.