i have a computer with linux on it and dont know how to download stuff

Computer Type: Laptop
System Manufacturer/Model Number: dell
OS: 7 and linux
CPU: dual core
Hard Drives: 250 gig
Browser: firefox
Antivirus: none

Computer Type: PC/Desktop
System Manufacturer/Model Number: Ignatz Special; 4 speed manual gearbox; factory air conditioning; one of one
OS: Windows 7 Home Premium SP1, 64-bit
CPU: Intel Skylake i5-6600K, not overclocked
Motherboard: AsRock Z170M Extreme 4, micro ATX
Memory: 8 GB HyperX DDR4-2666 (2 x 4 GB)
Graphics Card: none; graphics are integrated on CPU
Sound Card: onboard: Realtek ALC1150; external: USB Behringer UF0-202
Monitor(s) Displays: Dell S2340M 23 inch IPS
Screen Resolution: 1600 x 900
Keyboard: Microsoft 200 6JH-00001 USB
Mouse: Dell or Microsoft optical wired; USB
PSU: Rosewill SilentNight 500 watt fanless, semi-modular
Case: Antec Solo II
Cooling: Noctua NH-U12S; Noctua F12 intake, Noctua S12A exhaust
Hard Drives: System: Crucial MX100 series SSD, 128 GB; Data: Samsung Spinpoint 103SJ, 1 TB; Backup: WD Caviar Green WD30EZRX-00D8PB0, 3 TB
Browser: Pale Moon
Antivirus: Microsoft Security Essentials and Malwarebytes Premium
Other Info: All fans PWM; speeds at idle: CPU circa 500 rpm; intake circa 600 rpm; exhaust circa 600 rpm; CPU temps 27 idle and 47 C load in a warm room (27 C/81 F) when running Intel Extreme Tuning Utility stress test.