I know there are plenty of places that explain how to do this but I will do it as well.
First the step is to get some potting soil, some pots and of course seeds. To start seeds the best thing to get is a set that comes with a tray with a bunch of small plastic or sometimes with disks that if you water them become pots. Also, will need some potting soil almost any will do. Then when you get home and it is warm enough to start them you should fill them about 75-80 % to the top like these.
The next step is to put a few seeds in each pot. Some big seeds like squash and pumpkins put about two seeds in each pot. Some of the smaller seeds you should put in few more because some the seeds wont germinate and later they can be seperated and put into individual pots.
After that is done cover the seeds with more potting soil.
After a couple weeks you should get a tray of plants that kind of look like this.
Place the the tray in a warm spot, does not have to in the light for until the come out of soil. Then place in a window, the best spot would have sun all day. Water as soon as you are done planting, the best way is to pour the water into the tray. The soil will absorb the water as it needs it, also it the seeds will not be be disturbed. Most plants have what referred to as seed leaves. These are actually inside the seed also are do not resemble the leaves that will the plant will eventually have. Plants of the same family such as peppers and tomatoes will have the same shape of seed leaves.