Hello, im dual-booting Ubuntu on my computer with windows 7. When I use windows the internet works fine, however when i switch over to Ubuntu and click on network manager no wireless networks appear.

Can someone help me?

What make/model computer and what type of network chip?

type the following code in the terminal
a gedit window will open
just copy the contents and paste it and reply

I have a acer aspire 5517.
And the results from the gedit window is:

00:00.0 Host bridge: Advanced Micro Devices [AMD] RS780 Host Bridge
00:01.0 PCI bridge: Advanced Micro Devices [AMD] RS780 PCI to PCI bridge (int gfx)
00:04.0 PCI bridge: Advanced Micro Devices [AMD] RS780 PCI to PCI bridge (PCIE port 0)
00:05.0 PCI bridge: Advanced Micro Devices [AMD] RS780 PCI to PCI bridge (PCIE port 1)
00:11.0 SATA controller: ATI Technologies Inc SB700/SB800 SATA Controller [AHCI mode]
00:12.0 USB Controller: ATI Technologies Inc SB700/SB800 USB OHCI0 Controller
00:12.1 USB Controller: ATI Technologies Inc SB700 USB OHCI1 Controller
00:12.2 USB Controller: ATI Technologies Inc SB700/SB800 USB EHCI Controller
00:14.0 SMBus: ATI Technologies Inc SBx00 SMBus Controller (rev 3c)
00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)
00:14.3 ISA bridge: ATI Technologies Inc SB700/SB800 LPC host controller
00:14.4 PCI bridge: ATI Technologies Inc SBx00 PCI to PCI Bridge
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
01:05.0 VGA compatible controller: ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics]
02:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g (rev 01)
08:00.0 Ethernet controller: Atheros Communications Atheros AR8132 / L1c Gigabit Ethernet Adapter (rev c0)

Which version of Ubuntu are you in? Or, to be exact, which kernel version? BCM4312 is supported as of kernel ...29.
I would recommend you to either update kernel to this level or try *buntu 10.10.

Try this:

http://wireless.kernel.org/en/users/Drivers/b43

It has helped many folks get those pesky broadcom chips working.

HTH
Dave