First I want to say if you are using a book throw that book way and get a different one, unless you are skipping around. I think you are missing some basics of how verbs work. Also please learn hirigana too romaji is hard. lol.
Lets look at the verb you are using. First you have dictionary form
yomu
よむ
That is the "base" of the word. That is dictionary and where everything starts from. It is also short form present affirmative too.
For long form you will change the mu to mi. Or in another way you will take that final u and turn it into an i then add masu or masen so.
yomu -> yomi -> yomimasu (final)
よむ -> よみ -> よみます
yomu -> yomi -> yomimasen (final)
よむ -> よみ -> よみません
For short form present negative it has a similar concept of changing the u to something else. This time for the short form present negative you are going to change that u to an a. So the same sequence
yomu -> yoma -> yomanai (final)
よむ -> よま -> よまない
As you might have seen since this is a u-verb (godan) then the last "sound" or in romaji the last character changes to something else before adding. So lets look at potential form now which is where you started
For potential form we are actually turning the u-verb (godan) into a ru-verb (ichidan), and we follow the same pattern we change the u to an e. Then we just add ru.
yomu -> yome -> yomeru
よむ -> よめ -> よめる
And to jump to your final part of step 1. since we have changed yomu into a ruverb(ichidan) now we can do a simple ru-verb conjugation.
yomeru - yomemasen
よめる -> よめません
You need to forget "base 1" "base 2" "base 3" way of looking at verbs and learn the word then the proper flow of conjugation. Will make things much less confusing for you.
here are some links to my blog explaining things in a bit more detail
Understanding u-verbs and ru-verbs
Japanese Verb Conjugation Present and Future
Japanese Verb Conjugation Past Tense
Short Form Japanese Verb Conjugation Present Tense
And seriously please learn kana
Learn Katakana and Hiragana in 2 weeks
I have more than that, but that should get you started.
Hope some of this has helped.