There is so much to learn where do I begin? LOL
Read what we have talked about and shared here. Read as many of the articles we have on our site pages. If you have any questions at all, don't hesitate to ask. The nice thing about adoption is you will already know their temperament and their health, whereas if you read some of what we have discussed in the past, with a puppy you could get one of perfect health, or you could end up with major surgeries. Since you already have a dog I would recommend them to meet on uncommon ground, like a park or something. good luck and keep us posted!
Welcome to the site!