Imessage for mac os x 10.5.8 or 10.4.11

Hello my name is Byron i am full Deaf

i have Mac os X version 10.5.8 PowerPC G4 1 GB SDRAM i need want know do have anyone have old save that from imessage download in my desktop like Ipad 3 64 have imessage iphone have also i want also in my computer old one but know that i can't affords from that imac really my friend was gave me PowerPC Mac os 10.4.11 update 10.5.8 understand dont have imessage with me i really need want know how can i downlaod because i need see on my desktop i can charger on ipads leave on there easy for me please i need want know where can i download that from 10.5.8 i need read on my imessage on desktop please i need want know thanks