Okay clearly you need to learn the basics of Maya, i would suggest you download some of the free tutorials here such as modeling a hand https://simplymaya.com/autodesk-maya-...=326&sub_cat=0

You should also do the tutorials in the help documents because that will give you a basic understanding of the tools in Maya and most likely answer a lot of your initial questions about basic use.

Richard is right , you need to combine your meshes and then merge the vertices on the joins.

Also if you need to make a smoothed edge sharper you can reinforce it with another edge close to it.

Finally one thing i forgot to mention in my previous post is that to get out of smooth preview and back to your low res view hit 1 on the keyboard with the mesh selected.