。
I went to that lawyer seeking legal help.
Literal
Legal-[上] help [object-を] seeking that lawyer [possessive-の] place [to-へ] went
The suffix ~上 (じょう) attached to a noun means 'from the standpoint of X, in terms of X, on X' — e.g. 法律上 (legally speaking), 仕事上 (work-wise), 形式上 (formally). 求めて is the て-form of 求める (to seek) used as a conjunctive purpose marker: '(I) went to the lawyer, seeking help'.