[littlefrog]

Just to add to the fine advice of Ray, the pictured plant is most certainly not a dendrobium. It is an oncidium. Probably Sharry Baby "Sweet Fragrance".

The second plant is indeed a dendrobium. No idea what the cross is though.

But, don't let that stop you. If you want to play with seeds, go ahead and set a capsule. Take a flower or two off the plant and dissect them. The pollinia will be obvious (I hope), and at the tip of the column (the protrusion in the center). Most times pollinia are covered by an anther cap. Take the pollinia off of a flower (with a toothpick, or a pin). What you have left is a socket where the pollinia were, and immediately behind that (proximally, towards the center of the flower) a 'wall'. That has a fancy name too, don't worry about it. The other side of that wall is where the pollina are placed, this is the stigma. It should be slightly sticky. Take a pollinium (or two), and place them on the stigma of a flower that is still attached to the plant. If they don't stick, use a drop of honey or wet them with some spit.

You want to use a reasonably fresh flower as the pollen acceptor. If you do it right, the flower will shrivel and the ovary (everything behind the flower) will swell up. Eventually this will ripen, and split, revealing your seeds which will be quite small and probably mostly on the floor by this time.

Different orchid flowers are constructed slightly differently, although they all have the same general arrangment of parts. The column should always contain both pollen and stigma (except in a cycnoches or catasetum, for example, which are weirdos...). Sometimes the flower will shrivel almost instantly after pollination, sometimes it hangs on for quite a while. Capsules ripen at differing times for different genera.

Naming... You should put a tag on any cross. And list it as as pod (the plant carrying the capsule) x pollen. Remember that as ladies first. Always put a date of pollination on your tag. Hang the label right from the ovary, so it doesn't get lost.

All that said, feel free to set some capsules (not too many, you can kill plants this way). Feel free to germinate some of the seeds in the laboratory, and perhaps even replate the protocorms. But I wouldn't try to grow out any of the progeny. Not on this cross anyway. For that, make sure you start with plants with proper identification. There are enough no name plants in the world. Don't worry about making a 'stupid' cross. Yes, it is possible. But that is how we learn. Of course it is also nice to do some research ahead of time, can save a few years of effort.