It's easy. Just set up your student(s) and courses as you normally would. Then fill in the school year calendar with dates from the previous school and round out the calendar with dates that will complete your school year. You only fill in milestone dates such as the start of each quarter and holidays and breaks. Then begin using the Lessons screen to make assignments and create lesson plans. There is no need to fill in assignments from the previous school -- just pick up where you are. Also fill in any absences from the previous school.
HomeSchool Easy Records tracks attendance in two ways -- "Days Attended" and "Days Earned." The days attended is a count of whole days the student is in school, and the days earned is calculated by the program from time earned in all of the lessons you have recorded. Since you haven't been entering lessons since the beginning of the year, the time earned will only reflect the time since you began entering lessons. (You can actually get around this by entering BIG numbers -- the actual equivalent of minutes earned in each subject from the previous school -- on the "first day" of homeschool.)
As far as the "days attended" -- the software will actually show the true number of days, including time from the previous school, even if you don't use the "big numbers" trick. One other thing -- with HomeSchool Easy Records, you don't have to "check off" each day that a student is IN school -- you only need to enter any absence days. The program makes the assumption that each day with lessons is a day the student is in school. This saves you typing and saves you time!