I'm trying to install YAF into an existing .Net website.
Following the instructions at:
https://github.com/YAFNET/YAFNET/wiki/YAF.NET-Integration-in-to-an-existing-ASP.NET-Application 

I think I have followed the instructions.
I believe I have put the followed where to put the various YAF components. My directory structure looks basicially like this:
MyWebsite
......\Forum
................default.aspx
................default.aspx.cs
...............\Properties
................\Styles
................\Forum
.............................\controls
.............................\editors
.............................\images
.............................\install

Does this seem correct?

I'm concerned as when I attempt to start the forum software, the install package isn't found. Here's what I start the forum with:
http://192.168.10.107/forum/default.asxp 
(The IP is the IP assigned to the parent website which is working fine)

I get:

Server Error in '/' Application.
The resource cannot be found.
Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly.

Requested URL: /forum/install/default.aspx

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1025

Which leads me to believe I don't quite have the directory structure laid out correctly.

Any suggestions?

It looks like you have one too many /forum directories. I run my site with ASP.NET like the Sample Application and I have my root directory and in that a subdirectory called /forum and have all of my YAF files copied into there.

That's what I was thinking as well.
But where do the default.aspx, default.aspx.cs, site.master, site.master.cs that are in the sample webapp distribution go then? The root directory of my parent directory? I already have default.aspx for the parent website. I did have to move the site.master to the parent root directory already to get as far as I did. I'm guessing I'd just copy what is there to my parent root directory and then fix any file name collisions that would happen. I'm thinking the rest are probably okay

That's what I was thinking as well.
But where do the default.aspx, default.aspx.cs, site.master, site.master.cs that are in the sample webapp distribution go then? The root directory of my parent directory? I already have default.aspx for the parent website. I did have to move the site.master to the parent root directory already to get as far as I did. I'm guessing I'd just copy what is there to my parent root directory and then fix any file name collisions that would happen. I'm thinking the rest are probably okay

Site.Master would be in the root.

You are installing YAF fresh into an already built WebForm website, correct?

Okay, I've gotten further along.

Now at the "Initialize Database" part of the install process and getting the following error:

FILE:
mssql/tables.sql

ERROR:
Failed to update database "D:\FTPDIRECTORY\FORUMJOINTWEBSITE\APP_DATA\DATABASE.MDF" because the database is read-only.

STATEMENT:
CREATE PROCEDURE [dbo].[yaf_drop_defaultconstraint_oncolumn](@tablename varchar(255), @columnname varchar(255)) as
BEGIN
DECLARE @DefName sysname
............

I've got Security Permissions on App_Data folder and the Database files in it set to Full Control for pretty much everyone in trying to get beyond this. Do I need to go into SQL Express Management Studio and change some permissions on the actual database?

Check the mdf itself if it has the read only flag set on. And you need give user ASPNET and NETWORK SERVICE Modify control over the App_Data directory.

Found the problem. The App_Data directory was Read-Only. Used IIS 6 to enable write permissions on the App_Data folder and got the install process to finish.

Thanks for the help.

Now to explore.