login，its -ing form,
login, means entering into computer system, if use -ing form, do I have to double "n" before -ing? can't find it in a dictionary,
one more question if you know Chinese,
how to translate 中国循环经济网 into Englsih, can I say:
“Offcial website for China Circular Economy”，正式的名称，对吗，
thank you for your help,

Question

login，its -ing form,
login, means entering into computer system, if use -ing form, do I have to double "n" before -ing? can't find it in a dictionary, 
one more question if you know Chinese,
how to translate 中国循环经济网 into Englsih, can I say:
“Offcial website for China Circular Economy”，正式的名称，对吗，
thank you for your help,

Answer

As for the first part of your query, I would say login is a noun and as such cannot take a gerund, since gerunds are formed from verbs. the verb would be  'to log in' and the gerund would then be 'logging in'.

As for the second part, I would say: The Official Website of China's Circular Economy. However, I would not swear to the accuracy of this translation.

Answer

"To login" must be treated in the phrasal verb form, "to log in".  So "log" is changed.  I logged in, she logs in...

The -ing form you need is "logging in". "After logging in, you will be directed to your profile."

(If you're wondering, "loginning" sounds comical.)

I can't really answer the Chinese translation, but "circular economy" is a proper phrase.