Hopefully this is simple enough (I haven't used splunk that much):
Given a log file that looks like this:
1/1/11 John 25 Notes
..
How can I apply "labels" to each value (e.g. the second column would be "NAME") so that I can then do searches like: NAME=John ?
You can perform a search time named field extraction with something like this in props.conf
[my_sourcetype]
EXTRACT-extract_my_fields = (?<datetime>\d+/\d+/\d+)\s+(?<name>\w+)\s+(?<col3>\d+)\s+(?<col4>\w+)
Have a look at the interactive field extractor, it should be able to help you;
http://docs.splunk.com/Documentation/Splunk/latest/User/InteractiveFieldExtractionExample
If you have trouble with it you could create a regex to identify all the fields in the event and use the props and transforms configuration files. Have a go and if you have any troubles feel free to update your question with your attempts!
http://docs.splunk.com/Documentation/Splunk/4.3/Admin/Transformsconf
http://docs.splunk.com/Documentation/Splunk/4.3/Admin/Propsconf
For a headstart a regex like;
\d+/\d+/\d+\s+(\w+)\s+(\d+)\s+(\w+)
Would capture JOhn, 25 and Notes into a different group each (group 1, 2 and 3 respectively), look at the "FORMAT = " part of the transforms config on how to apply a fieldname