[kraft021]

You cannot find the translation because まいりましょうぞ is not a common way of saying "shall we go?". It is an accent of an elderly guy.
The proper way of saying it is まいりましょうか (mairimashouka).

I think it's easier to learn words first and then learn to form a sentence.
In this case, a verb used on this sentence is a まいる (mairu) (go or come in English).
まいる turns into different forms depending on how it is used.

e.g.
まいりました (mairi mashita) (I came here in polite way)
まいります (mairi masu) (I will go in polite way)
まいりましょうか (mairi mashouka) (shall we go in polite way)

Other Japanese word たべる (taberu) (eat in English) can be applied in same way.
たべました　(tabemashita) (I ate)
たべます (tabemasu) (I eat)
たべましょうか (tabemashouka) (shall we eat?)