Chromatin is tightly condensed to chromosomes only during mitotic/meiotic phases and not all the time. In your body, right now there are several cells which are not dividing and hence the DNA is freely available coiled around histone proteins. Transcription machinery access DNA by unwinding DNA from histones (histone deacetylases) initially. Later DNA gyrase unwinds the coiled DNA (like zip open) where the transcription machinery acts.
