Hello and welcome in this Forum, i'm also new myself. Do you play Career or Sandbox? If career, do alot of missions to mun and minmus, like orbiting and landing. explore different biomes on them, this will give you hell-lotta science. after this, send probes to different planets and send the science back to kerbal, so you dont have the need to bring them back, but you also won't lose any kerbals. Do all this Stuff until you have atomic engines, you will need them to do interplanetary mission. I just had a manned flyby on duna last week and i went all this way through career, but so i learned alot of the techniques in KSP. And last but not least: Look for Scott Manley on Youtube. He made a whole KSP Tutorial section and he is literally a KSP god... So, have fun and I hope I could help you with your problems MarkedOne out