J.H.
Being a Stay at home can be very rewarding and isolating. As other people have probably suggested getting out to playgroups etc. are great ways to meet people. However, it may or may not take care of the friend part.
I think a good step to being a friend is to become more aware of yourself and who you are. What are your strengths and challenges. What qualities do you value in a friend? What are your challenges and strengths in terms of these qualities? Where do you get your energy from? Are you an extrovert who gets energy from groups and crowds or are you an introvert who gets energy from self introspection and reflection. Sometimes it can be very tiring for introverts to be in social settings. I am an introvert so I know to make friends, I am going to have to go out of my comfort and energy zone to interact with people. Introverts can be quite content to have a few good friends rather than to surround themselves with many friends.
Try not to take things personally. People are so busy. You might have to take the first step to making new friends. If you can find child care for an hour get involved in volunteering somewhere. This is a great way to meet other people, get time away, and feel like you are making a social contribution, and developing other interests. Be open to friendships. Friends come in all ages and might look differently than what you think.
Good luck.
J.