How do I download a report for my entire AdWords account?

Below is an example of how to run, then download, an overall account report; the process is similar for each report type.

Part 1: Create your report

To run a report for your entire account:

Log in to your AdWords account.
Click on the Reports tab.
Select Account reports.
View: Select a viewing option from the drop-down menu (summary data, or daily, monthly, quarterly, or yearly metrics).
Date range: Select the date range for your report.
Ad Distribution: Select the AdWords distribution network for your ads (the entire Google Network, the search network, or the content network).
Conversions: If you have activated conversion tracking, select whether you'd like to include your conversion statistics.
Report name: Enter a unique name for your report.
Scheduling: If you think you'd like to repeat the report later, select 'I want to run this report in the future.' Then choose a daily, weekly or monthly run schedule, or choose 'on demand (only when I request it)' to save the report to be run later manually from your Download Center.
Email: Check this box to receive an email notification for your newly created report (and all future reports from this same template). If you'd like to change the email address(es) associated with your notifications, update your email address list at the bottom of your Download Center.
Click Create report.
Part 2: Download your report

When your report is finished:
Log in to your AdWords account.
Click on the Reports tab.
Click Download Center.
Click the report you would like to view.
Select the format in which you'd like to download your report: .csv (for Excel), .csv, .tsv, or .xml.

Also, can you advice me on the meaning of the various fields in the Adwords report like Transactions, Cost/Transaction, Total value, Sales Count, Sales Value, Sign-ups count convey?