Windows 7: Dictionary for Language Bar

I'm new comer of Japanese language, so when I type a word, there are some mistakes. I want when I use language bar, it will have function to notice words for me (this often in MS Word, but I still want for many others such as browser...)

I have found in language bar function dictionary tools, but I don't know purpose of this tool.



So my question is :
1) what is the purpose of function dictionary tools.
2) how I can add a dictionary to language bar, and notice words when I type.

Thanks