How do I build a time delay circuit?

Time delays that are frequency independent are difficult. Filters delay different frequencies by different amounts.

If you only have one frequency that needs to be delayed, a simple RC circuit will do this. If there is a wide frequency band, you need some sort of special IC that uses charge transfers to make a fixed delay.

So, more details will help.

edit, check this part:

SAD-1024 DUAL ANALOG DELAY LINE

This part uses a clock to sample the analog input and to then pass that sampled signal through a set of 512 "buckets" to the output.

.

It called Delay Line, not a high pass filter. This parts was existed in most old type color TV set. It is a piece of 6 inches long about 100 turns of coil that has the delay time of 1us to delay the Y-signal. To delay a few ms as your requirement, the coil shall be a few thousand turns.

See this link as an example to make delay line....

http://www.hawestv.com/mtv_color%5Cdelayline.htm

Bessel filters provide delay for frequencies up to a certain value. You have to look up details of bessel filters and see how much delay can be obtained and up to what frequencies it will provide this. Beyond that frequency, the signal amplitudes reduce. A 60 Hz filter might be able to give you 16mS delay for signals from dc to 60 hz if it is an eighth order filter.See design and analysis of analog filters by various authors in google books...And also an EDN article on bessel filters.

www.edn.com/contents/images/6305351.pdf

Higher delays are obtained by digital means. Store converted data in memory and read it back after delay..

For some hundred dollars you may get a digital postpone consequences pedal for guitar/vocals with a great adequate postpone. or you ought to get an A/D card for you computing device, then write utility to digitize the audio, save it and then play it back 7 seconds later.