Today I have felt a bit melancholyic, the reason: I´m inat the last part of my ebook, this ebook I recommend ithis ebook because itprovides a lot of tools for improvementing your habits.

It has been an amazing experience since the first page until the currently page; this book teaches a lot of ways to face the day -to -day life.

I put 'life' at the end because 'day-to-day' is an adjective, so it makes sense gramatically to put a noun like 'life' in front of it.

I hope to follow the most of the instructions and improve my habits and to become in a great person.

Today I have felt've been feeling a bit melancholyc, tic. The reason: I´m in the last part of my ebook, this ebook. I recommend ithis ebook because it provides a lot of tools for improvementing your habits.

"Melancholic" or "melancholy" are both acceptable as the adjective here. (I chose "melancholic" for my correction, but there's no real difference in this situation.)

"Today I have felt..." is unusual, but there are multiple ways you could reword it:
"Today I feel a bit melancholic" or "Today I'm feeling a bit melancholic" = You are *currently* feeling melancholic. (There's a slight difference between these two, but I don't really know how to describe it, and in this context they're nearly equivalent.)
"Today I've been feeling a bit melancholic." = You started feeling melancholic earlier today, and that feeling has continued to the present; you are still feeling melancholic.
"Today I felt a bit melancholic." = Earlier today, you felt melancholic, but you don't feel that way right now. (This probably isn't the best choice in this context.)

It has been an amazing experience sincefrom the first page untilto the currently pag one; this book teaches a lot of ways to face the day -to -day.

"Currently" is an adverb, so you'd want to say "current page" instead of "currently page". I also replaced the second "page" with the pronoun "one", since it's redundant to say "page" twice.

"Since [x] until [y]" isn't a typical combination in English - the appropriate phrasing is "from [x] to [y]".

(You could also replace the whole phrase "from the first page to the current one" with "from beginning to end", which is a more idiomatic expression.)

The use of "day to day" as a noun sounds a little odd to me, but apparently it is acceptable; it's typically hyphenated ("day-to-day"), though. You could also use it as an adjective: "day-to-day life", "day-to-day situations", etc.

I hope followto make the most of the instructions and, improve my habits, and to become in a great person.

You could say "I hope to follow most of the instructions", but I think the idiom "make the most of" is more appropriate here.