1. Your question belongs in the "Help with Reception" forum.
2. Post a TV Fool Report (follow the instructions here
3. What kind of antenna are you currently using (model number).
4. What direction is the antenna aimed?
5. What kind of roof do you have (shingle?)? What is the siding on your house (stucco over metal mesh? metal wrap of some sort?)? -- What the the antenna "look through"?
This may seem like a lot of information but it is necessary. If you have the wrong antenna or if it is pointed in the wrong direction for the channels you want, an amplifier might not help. Attics can be very unfriendly.
You might also list the channels you get and those that you don't get but want (listed in the order of your TV Fool Report).