To translate "on Tuesday mornings", "on Wednesday evenings" etc., form a compound noun consisting of the name of the day followed by the adverb for the appropriate part of the day - "morgens", "vormittags", "abends" and "nachts". Such compound adverbs do not start with a capital letter. For example:
Wir treffen uns freitagabends zum Kegeln.
(We meet on Friday evenings and go bowling.)
Ich leihe mir donnerstagnachmittags ein Video aus.
(I rent a video on Thursday afternoons.)
Wir spielen sonnabendvormittags Fußball.
(We play football on Saturday morning.)
