I think I posted some map loading code a day or two ago, but if you just want to put a picture on the screen it may be easier to draw it in smile tools drawing program, then load it from file. Something like:
DEF TITLESCREEN
DIM X%, Y%, MSG$
LOAD "GRP0:SPACETITLE", 0, 0, FALSE
GCOPY 0, 0, 0, 400, 240, 0, 0
MSG$ = "PRESS A BUTTON TO PLAY"
X% = (49 - LEN(MSG$)) * 8
Y% = 20
GPUTCHR X%, Y%, MSG
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プレイ済み