There are lot of tutorials and guides in the Internet about Sitecore search. It's very similar in Sitecore 7 and Sitecore 8 so you can use both of them.
First thing you should check is Sitecore documentation: Developer's Guide to Item Buckets and Search (the most interesting part for me starts from chapter 5.3).
In the shortcut, create a class for your items (it can inherit from Sitecore SearchResultItem
class but it's not required if you want to handle standard Sitecore fields by yourself), e.g.:
public class Person : SearchResultItem
{
[IndexField("firstname_t")]
public string Firstname { get; set; }
[IndexField("surname_t")]
public string Surname { get; set; }
}
and use code like that to get the results:
using (var context = ContentSearchManager.GetIndex("my_text_index").CreateSearchContext())
{
IQueryable<Person> query = context.GetQueryable<Person>().Where(p=> p.Firstname.Equals("John"));
}
And that's it. You don't need anything else to start using Sitecore Search API with Sitecore 7.
And here is a really nice "Sitecore 7 Search - a quickstart guide" article