How to upgrade a normal desktop pc to a gaming pc? (specs below)?

system model- Acer Aspire XC -605
processor- intel core i3-4130 cpu @ 3.40GHz 2 cores, 4 logical pro…
RAM- 4 gig

basically, i have very limited PC knowledge and would love some help in upgrading my desktop to run games well (I like minecraft modpacks like FTB infinity but it often has some insane framerate drops) any info into what i should be looking for and how much it'd cost would be incredibly helpful:) thanks xxx

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