If you want to regress the last column from a 100-long time series, this is how you could write your dataset:
class CustomDataset(torch.utils.data.Dataset):
    def __init__(self, data):
        self.x = data[:,:-1]
        self.y = data[:,-1]

    def __getitem__(self, index):
       return (self.x[index,:], self.y[index])

   def __len__(self):
       return self.x.size()[0]

You can then access your data using either the naive for x,y in MyDataset: approach, or use a dataloader.
For more details on the Conv1D, you can refer to this post here 4