how do i set up network preferences and what i share

Do you mean your Mac as the Wireless Base Station?

Click on the Airport icon in the Menu bar at top, choose Create Network,when new window comes up click Require Password,it's not very secure,but choose 128 bit WEP

System Preferences>Sharing, check & highlight which services you want to share,you'll see choices of what to share & who to share with.

How do i safely set up wireless network and sharing

If "Safely" is important, then you configure a WiFi router with WPA2 encryption and use a good WiFi password.

Turning your Mac into a WiFi base station, as BDAqua has indicated only uses WEP encryption which can be cracked in less than a minute by anyone that is in range and wants to run some easily available WEP cracking software. WEP is only good for keeping honest people out.

For Sharing, it depends on whether you want it to be with yourself via other system you own or with others. Sharing with yourself and being Safe just needs a good Mac login password after you have enabled whatever sharing services you desire.

Actually a little more information about what you want, whether you have a WiFi base stations that support WPA2 encryption already, or if you want the Mac to be the base stations.

What devices are you going to share with?

Who will be using those devices (and how much trust to you have in them; your spouse you may have unlimited trust, but your neighbor not so much).

What kind of sharing? Files, printers, screen sharing, music, photo albums, etc....

I have a wireless cable modem, sharing internet with neighbor

NOTE: generally ISP's does not approve of sharing with anyone outside your house hold.

If neighbor is close enough to access your WiFi signal, then you need to mostly give your Mac a good password so that your neighbor (or your neighbor's kids) will not get into your Mac.

If you do not wish to share files, printers, screens, then there is not much else to be done.

If your signal is not strong enough, then your options are:

• Move the WiFi base station closer to your neighbor
• get a WiFi extender and place it near your neighbor
• bury an ethernet cable between your houses
• other

No, I'm really new toto this, and I'm using a cable modem, and then I use my new IPhone 6s+ and new I-Pad on that wifi connection, but when I use my I-Phone and other IBM PC type tablets, laptops, I-Phone and I-Pad, I'm afraid. That everyone in my apartment building can use my unlocked modem. I want it to be open to all my devices, but not to everyone in my building and from the street below.

01ive wrote:

No, I'm really new toto this, and I'm using a cable modem, and then I use my new IPhone 6s+ and new I-Pad on that wifi connection, but when I use my I-Phone and other IBM PC type tablets, laptops, I-Phone and I-Pad, I'm afraid. That everyone in my apartment building can use my unlocked modem. I want it to be open to all my devices, but not to everyone in my building and from the street below.

Then you cannot have an open WiFi network.

You must configure your WiFi router with a WPA or WPA2 WiFi password. All the devices you specify will be able to enter a WiFi password, and will be able to remember that password, so you do not need to keep re-entering it. They will most likely prompt you to enter the password, such as this display from an iPhone:

It will then remember the password for your Router from that point forward.

I'm sure there will be similar prompt from your Windows system as well.

If you keep an open WiFi network (no password), then EVERYONE that can see your signal will be able to join your home network. In some cases they may not even know they have joined your network, as their device may decide your open network is available and the best choice (as in it is the least trouble).

When you got your WiFi router, it should have included instructions on how to set it up, and give it a WiFi password. If now, and you got it from your ISP, then contact them as ask for help setting up a WiFi password. Or get the Make and Model number off the WiFi router and Google it for instructions (most are available on-line).