Hello Felicianicole,
 
The alphabet is a very abstract concept, and an especially hard one for a first grader, I think.
 
If you want to use the alphabet to help her, you could have an alphabet strip at her workspace, and you could refer to it as you're helping her look up words.  You could think about this as similar to using a number line for solving addition and subtraction questions.  For example, if you're looking up a word that starts with the letter "c", you could look at the alphabet line, and she'll see that she needs to look at the beginning of the dictionary.  Etc.
 
You could make a letter tab on the side of the page for each new letter.  That way, she could figure out the beginning letter of the word she's looking up, and then look for that letter tab.
 
A children's thesaurus might be more helpful for her.  She could then look up topics, like "animals", or "cats", etc.
 
If these are all too difficult for her, then you could look up the words, and she could watch how you do it.  You could tell her what you're doing, as you do it, so that she's aware of the thinking that's involved in the process.
 
Sincerely,
Sylvia HS,
Reading Specialist, Author