Kurashikku myuujiku ga suki desu ka.
Are you sure you want to use a Japanised English word here? I would use クラシック音楽 (kurasikku ongaku) instead.
Shigatsu no ni-jyuu-yokka no kayoobi no yoru wa hima desu ka.
Should be ４月２４日火曜日の夜 (sigatsu nijuuyoka kayoubi no yoru). What you wrote would be like "the evening of Monday of the 24th of April".
Watashi wa kurashikku konseeto no chiketto desu. Isshoni konseeto e ikimasen ka.
This means "I am a classical concert ticket". You might want to use the verb 'have', which is 持つ (motu). So you'd say 私はクラシック音楽のチケットを持っています (watasi ha kurasikku ongaku no tiketto wo motte imasu). I'd also leave out 'konsaato e' in the second sentence, otherwise it would sound like "I have classical concert tickets. Would you like to come to a/the concert with me?"
Maitsuki gurai kurashikku konseeto e ikimasu.
I think you're trying to say 'I go almost every month'. If so you'd say 'ほとんど毎月コンサートへ行きます' (hotondo maituki konsaato he ikimasu). The 'hotondo' part means 'almost'.
Konseeto wa gogo nana-ji desu.
Use the verb 'to start', which is 始まる. You also say 'siti ji' for 7 o'clock (or "shichi" if you prefer to think of the pronunciation in that way). I'd also leave out 'konsaato'. So you'd say 午後７時に始まります (gogo sitiji ni hajimarimasu).
Gogo roku-ji han ni eki no mae wa aimashoo ka.
Why have you got 'eki no mae' as the subject? The subject is 'we' (i.e. you and your friend). 'eki no mae' is the location where the action takes place, so you should use the particle で. Also, leave out the subject (we), which you've kind of already done. So you'd have 午後６時半に駅の前で会いましょう (gogo rokuji han ni eki no mae de aimashou).
Pretty good effort though for a beginner. You should be proud of yourself. Now for your own good, stop writing in romaji, stop thinking in terms of English pronunciation (i.e. ち is not really 'chi', し is not really 'shi', and ら、り、る、れ、ろ is not pronounced 'ra' 'ri' 'ru' 're' 'ro'). My teacher called me up on my pronunciation yesterday because I pronounced 冷凍 （れいとう, meaning "refrigeration） as "reitou", when actually it's more like "leitou". We'll it's not really that either. But my point is, as a beginner, get into good habits
Good luck!
