Please correct translation.

我干了一天，累死了(I am dead tired after working all day)
我要成为高下想变得更强壮。(I want to become stronger.)

Please correct translation.

我干了一天，累死我了(I am dead tired after working all day) or 做了一天工作, 真累死我了
我要成为更強高下(I want to become stronger.) This use of 強 by itself is most vague.  Chinese defines many kinds of being strong.  Since we have no context, I felt this is the best way to get around it.

Please correct translation.

我干了一天，累死了(I am dead tired after working all day)
我要成为高下(I want to become stronger.)

我工作了一整天，快要累死了。

我想变得强壮！

I have no idea why the previous corrections conducted by others didnot correct your grammar mistakes.

Tips:

干了 here in your sentence means did. Thus,you must mention what you did!

strong means 强壮（physically） as well as 坚强（Psychologically）.

when you use comparative words, just put a 更 in front thoses words. For instance, strong-强壮，stronger 更强壮. This works most of the time! 

Cheers!

Please correct translation.

我干了一天，累死了(I am dead tired after working all day) 我工作了一天，累死了。
我要成为高下(I want to become stronger.) 我要更强壮。